Our objective is to achieve a major advance in the technology used to assess disability in children and youth. Measurement and practical requirements to identify disability and to evaluate individual progress across pediatric age groups and care settings present a serious dilemma to current fixed-item survey instruments. To address these deficiencies, the principal aims of Phase I are to: (1) build a prototype computer adaptive testing (CAT) system based on existing Pediatric Evaluation of Disability Inventory (PEDI) normative and clinical databases; (2) estimate the accuracy and responsiveness of scores based on the prototype PEDI-CAT in comparison with scores for the full-length PEDI (PEDI-Fixed) using existing databases; and (3) evaluate reductions in respondent burden and acceptance of parallel versions of the PEDI-CAT and PEDI-Fixed in a pilot field test in four pediatric clinical settings. The product in Phase I will be a prototype version of a PEDI-CAT as well as preliminary evidence regarding how well it works. In Phase II, we will examine the questionnaire item calibrations of the original PEDI, add new items to broaden the age range coverage, conduct field studies to re-calibrate items, and create algorithms for a fully operational PEDI-CAT system. A practical and feasible PEDI-CAT will greatly improve the information used in making decisions about disability status, service eligibility, program needs and outcomes of rehabilitation interventions. The product of this SBIR project will be a marketable CAT system for the assessment of disability in children and youth between the ages of 6 months and 18 years. Adapted from the PEDI, and expanded to a broader age group, this new disability assessment will fill a critical void with a system that is more practical and precise. It will have the advantage of greatly reduced data collection costs, reduced respondent burden and will meet the standards of score precision required for clinical decisions at the individual patient level throughout the scale range. Many rehabilitation settings may also find this system helpful in meeting accreditation and institutional requirements for standardizing outcome monitoring in groups of children.